一物体以v0=1.5m/s初速度沿光滑斜面上滑,2s末仍沿斜面向上运动,速度大小为v1=1m/s,则物体的加速度a1=____________;如果增大斜面的倾角,保持物体的初速度不变,2s末物体沿斜面下滑,速度大小为v2=1m/s,则物体的加速度a2=____________. 答案:-0.25m/s2 ; -1.25m/s2【试题分析】—Did Mr. Li leave Shenzhen ______ Saturday morning? —Yes. He will be back ______ two weeks.
[ ]A. on, after B. on, in C. in, after D. in, in